Custom Fire, Smoke-Seal & Barrier Materials for Building Life-Safety Assemblies
H-O Products die-cuts and converts smoke-seal gaskets, non-combustible glass-fibre and mica barrier die-cuts, and firestop-adjacent closures into the material stack that closes the gap in fire and smoke doors, fire and smoke dampers, and through-penetration firestop details, built to your assembly drawing. The material carries its own classes per the maker technical data sheet; the fire, smoke, and leakage rating is earned by the tested, listed assembly.
Built for: smoke-and-draft-control door perimeter seals for assemblies tested to UL 1784, fire and smoke damper blade and frame seals for UL 555 / UL 555S, firestop-adjacent gaskets and closures that work with listed UL 1479 / ASTM E814 systems, and glass-fibre and mica non-combustible barrier die-cuts (Class A per ASTM E84).
Specify the gasket by the assembly requirement it serves, not by a rating it cannot hold. Smoke-and-draft-control door: a perimeter smoke-seal gasket at head, jambs, and meeting stiles, a listed component of an assembly tested to UL 1784 (3.0 cfm/ft² at 0.10 in w.g., ambient and 400 °F); reach for flame-resistant silicone sponge or EPDM foam. Smoke damper: a blade and frame seal for a UL 555S leakage class (Class I = 8 cfm/ft² at 4 in w.g..
The remaining zones and duties are mapped in the When-to-spec list on this page. Values are per the TDS on file; see the material reference below for ordering details.
Assembly-level, by designation (the rating belongs to the tested / listed assembly): UL 1784 (air leakage of door assemblies) · UL 10C (positive-pressure fire tests of door assemblies; UBC 7-2 legacy) · UL 555 (fire dampers) · UL 555S (smoke dampers) · UL 1479 / ASTM E814 (through-penetration firestops; F- and T-ratings) · NFPA 80 (fire doors) · NFPA 105 (smoke doors) · NFPA 92 (smoke control).
Material-level, per the maker TDS: ASTM E84 (surface burning; flame-spread and smoke-developed indices, Class A = 0–25 / ≤450) · UL 94 (flammability classes incl. V-0 on the rated grades) · ASTM D1056 (flexible cellular classes) · ASTM D395 (compression set).
- Door perimeter smoke seal (flame class): V-0 flame-resistant silicone sponge
- Door perimeter seal (economical): EPDM closed-cell foam
- Precision low-set closure: PORON® 4701 series
- Damper blade / frame seal: silicone foam / FR silicone sponge
- Non-combustible barrier (Class A): glass-fibre paper
- High-temperature barrier die-cut: phlogopite mica sheet
- Smoke / toxicity indices layer: low-smoke / low-flame / low-toxicity
- Firestop-adjacent closure: closed-cell neoprene sized to the annular gap
This guide is for life-safety and fire-protection engineers, architects and spec writers, and mechanical (HVAC) engineers specifying the smoke-seal gaskets, non-combustible barrier die-cuts, and firestop-adjacent closures that go into fire and smoke doors, fire and smoke dampers, and through-penetration firestop details — and for the procurement and sourcing buyers qualifying those made-to-order converted parts.
It states material selection in the standards and units these readers use, and it draws the compliance line where it belongs: the rating is earned by the tested, listed assembly; the converted gasket is a documented component evaluated per the maker technical data sheet (TDS).
Where are you in the spec process?
This page serves engineers who already know the gasket or barrier they want and engineers still assembling the requirement from the assembly it serves. Pick the path that matches where you are; you don't have to read the rest.
Send a drawing, get a quote
A perimeter smoke-seal gasket, a damper blade or frame seal, a glass-fibre or mica barrier die-cut, or a firestop-adjacent closure on your door schedule, damper drawing, or penetration detail.
Skip to the quote form →Build the spec from the assembly it serves
Six selection factors (seal force, flame and smoke class, elevated temperature, non-combustibility, firestop-system fit, and the compliance line), a checklist-driven gasket-set builder, and the material families with TDS-cited methods and by-designation standards language.
Start with selection factors →
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1Send drawingUpload a DXF, STEP, or PDF door schedule, damper drawing, or penetration detail, or describe the assembly and the gap. A sample part works too.
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2Material reviewEngineering reviews seal force, flame and smoke class, elevated-temperature and non-combustibility needs against the maker TDSs, and frames the standards language correctly: material classes (UL 94, ASTM E84) by TDS; assembly ratings (UL 1784, UL 555S, UL 1479) by designation, with the listing belonging to the tested assembly.
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3PrototypeSamples typically ship in 3–5 business days for common configurations on materials we keep on hand. Made-to-order; MOQ varies by material and part.
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4ProductionStandard production runs ship about 2 weeks after drawing approval, on flatbed die-cutting, CNC knife cutting for gasket sets, and kitting for door- and damper-level seal kits. Ongoing parts run with material traceability and lot-code TDS records.
Which assembly are you sealing?
Application Zones
Four assemblies define the work on the fire, life-safety, and smoke-control side of a building: the fire and smoke doors, where a perimeter gasket closes the leaf clearance so the assembly holds its air-leakage limit; the fire and smoke dampers, where blade and frame seals keep leakage in class; the through-penetration firestop details, where a compressible closure works with a listed system; and the non-combustible barrier die-cuts, where inorganic glass-fibre and mica sheet do the work no foam can.
In every one, the rating is earned by the tested, listed assembly; the converted part is a documented component. Click a tab to see the interface, the controlling property, and the families H-O converts for that zone.
Fire & smoke doors: the perimeter smoke seal
A fire or smoke door is a tested, listed assembly, and its weakest line is the perimeter clearance around the leaf. Where the code calls for a smoke-and-draft-control door, that assembly is tested to UL 1784 and must hold air leakage to 3.0 cfm/ft² of door opening at 0.10 in w.g., at ambient and at 400 °F, which is difficult to reach without a listed perimeter gasket at the head, jambs, and meeting stiles.
H-O and slits that smoke-seal gasket material to the door schedule: flame-resistant silicone sponge where a UL 94 flame class and wide temperature endurance drive the choice, and EPDM foam where an economical, ozone-durable perimeter seal suits the joint.
One line governs the drawing: the smoke-and-draft-control rating and the UL 10C fire rating belong to the tested door assembly and its listing; the intumescent edge seal is the door manufacturer's listed component; and H-O's converted gasket is a documented material evaluated per its maker TDS, not a rated part.
Fire & smoke dampers: blade and frame seals
A smoke damper closes a duct or wall opening so smoke cannot move through the mechanical system, and it earns a UL 555S leakage class (Class I is 8 cfm/ft² at 4 in w.g.; codes generally require Class I or II) plus an elevated-temperature rating not less than 250 °F. A combination fire/smoke damper is listed to both UL 555 and UL 555S.
The material that makes those numbers is the blade-edge, jamb, and frame seal, and it has to keep integrity at the rated elevated temperature or leakage climbs out of class in the event. H-O converts those seals from silicone foam and flame-retardant silicone sponge grades whose TDSs carry the temperature range the damper maker calls out, and slit to the damper drawing.
The leakage class and the temperature rating belong to the tested damper; H-O supplies the converted seal and its documentation.
Firestop & penetrations: closures for a listed system
Where pipe, cable, or duct passes through a fire-rated wall or floor, the code requires a tested through-penetration firestop system, and its performance is expressed as an F-rating (no flame passage) and a T-rating (no temperature rise above 325 °F on the unexposed side), harmonized between UL 1479 and ASTM E814.
H-O converts the firestop-adjacent components of that detail: compressible closures, collars, and gasket rings sized to the annular gap, from closed-cell families and, where the interface sees sustained heat, from inorganic barrier stock.
The critical framing is unambiguous: the F- and T-ratings belong to the tested firestop system, the listed sealant or wrap is the system supplier's component, and H-O's closure is a documented component of that listed system, never a substitute for it and never a rated part on its own.
Non-combustible barriers: glass-fibre and mica die-cuts
Some interfaces need a layer that does not burn at all, and that is inorganic territory. Glass-fibre paper (the MANNIGLAS®-class glass-fibre grades) is a thin, non-combustible barrier layer whose ASTM E84 surface-burning indices (a Class A result is flame-spread index 0–25 with a smoke-developed index of 450 or less) are reported on the maker TDS for the grade.
Mica sheet steps in where the interface also sees sustained heat: muscovite mica holds to about 500 °C continuous and phlogopite to about 700 °C, both non-combustible and dimensionally stable at flame temperature, with glass-fibre-reinforced flexible grades available for die-cutting into barrier pieces, standoffs, and high-temperature closures.
Where the location adds smoke and toxicity indices, the low-smoke/low-flame/low-toxicity family carries the layer. Die-cutting matters here: the barrier earns its keep only if it covers the footprint and survives handling, so edges, tabs, and tolerances come off the drawing.
Assembly requirement → material selection → converted gasket / barrier → production supply.
- 1Name the assemblyFire/smoke door, fire/smoke damper, penetration firestop, or barrier — and the requirement it must meet (UL 1784 leakage, UL 555S class, firestop system, ASTM E84 class).
- 2State the gap and the demandClearance to close, seal force, elevated-temperature and non-combustibility needs, and any smoke/toxicity index requirement.
- 3Choose the material familySilicone sponge, EPDM, PORON®, glass-fibre paper, or mica — matched to the class the location needs, per the maker TDS.
- 4Add adhesive / liner / tabPSA backing, release liner, or pull tab per the drawing, applied in-house with the validation framing for the substrate and exposure.
- 5Die-cut to drawingDie-cut, kiss-cut, slit, or kit the gasket, closure, or barrier to the door schedule, damper drawing, or penetration detail.
- 6Quote prototype or productionSample set for fit and submittal, then production with material traceability and lot-code TDS records.
Six decisions that drive your fire & smoke gasket spec
A fire or smoke gasket is a single-purpose part, and each of these decisions has one controlling property. Miss one and the failure is rarely immediate: a seal relaxes, a barrier is combustible in a Class A location, a smoke seal is missing behind an intumescent one, or a submittal stalls on a material that claims a rating it cannot hold.
Materials carry classes; assemblies carry ratings and listings. A UL 94 V-0 or an ASTM E84 Class A result belongs to a material grade per its TDS. UL 1784, UL 10C, UL 555, UL 555S, and UL 1479 / ASTM E814 belong to the tested door, damper, or firestop system. Write material classes on the gasket callouts, cite assembly standards by designation, and never let a drawing call a gasket "fire-rated", "smoke-rated", or "fireproof": the gasket is a documented component of a rated assembly.
Air leakage is evaluated on the tested door assembly at 3.0 cfm/ft² of opening at 0.10 in w.g., ambient and 400 °F. The perimeter smoke-seal gasket H-O converts is the component that makes that number achievable; the "S" (smoke-and-draft-control) mark belongs to the tested assembly, which is why this page cites the designation and never claims the rating for a material.
Read the six factors below in order. The first three set the seal itself (seal force, flame and smoke class, elevated temperature); the next two choose the barrier and place it in a listed system; the last one draws the compliance line so a submittal does not stall. Every factor names its test method, because in this application the documentation is part of the part.
Show all 6 selection factors tap to expand
Seal force: specify recovery, not thickness
Rule — match the gasket's compression class to the real closure force and pick a low-compression-set material so the seal survives years of cycling. A perimeter or blade seal picked to fill the gap on day one relaxes over time; when contact force falls below the seal threshold, the assembly no longer meets its UL 1784 or UL 555S leakage limit.
Specify the cellular class and compression behavior per ASTM D1056 / D395 on the TDS, and where the closure force is low and precision matters, PORON® microcellular urethane holds its seal force longest. State the closure force and the gap, and let the compression data pick the grade. [12]
Flame and smoke class: a material class, per the TDS
Rule — name the flame class (UL 94) and, where the location needs it, the surface-burning class (ASTM E84 Class A = flame-spread 0–25, smoke-developed 450 or less) on the material callout, and reach for flame-resistant silicone sponge (V-0 grades, BISCO® RS-series) where a V-0 class is required. These are material classes carried on the grade TDS, not assembly ratings. Where the design also specifies smoke and toxicity indices, the low-smoke/low-flame/low-toxicity family carries the layer.
Decide the class the location requires and write it on the gasket; do not let it imply a rating for the part. [7]
Elevated temperature: hold integrity at the rated demand
Rule — call out the elevated-temperature material grade the assembly's rating demands. UL 1784 tests door assemblies at 400 °F, and UL 555S requires a damper elevated-temperature rating not less than 250 °F; a seal that softens below that lets leakage climb out of class in the event.
Silicone foam and sponge hold recovery across the widest temperature band, which is why the damper and high-temperature door seals come from that family, with the range on the grade TDS. Match the seal's temperature grade to the assembly's elevated-temperature rating, not to the ambient duty alone. [4]
Non-combustibility: inorganic where nothing may burn
Rule — use an inorganic barrier where the location needs a layer that does not burn: glass-fibre paper for a thin Class A barrier (ASTM E84 indices per TDS), and mica sheet where the interface also sees sustained heat (muscovite to about 500 °C, phlogopite to about 700 °C).
Both are non-combustible and dimensionally stable at flame temperature, and both cleanly into barrier pieces, standoffs, and closures. Decide whether the location needs non-combustibility or a flame class; they are different requirements, and the wrong one puts a combustible seal where an inorganic barrier belonged. [7]
Firestop-system fit: a component, never the system
Rule — build to a listed through-penetration firestop system (UL 1479 / ASTM E814) and let the converted closure be a documented component of it. A compressible closure or gasket ring around a penetration is not the firestop; substituting it for the listed sealant or wrap voids the F- and T-ratings. H-O sizes the closure to the annular gap from closed-cell or inorganic stock, as part of the system, not in place of it. Name the listed system and the gap; the closure follows the listing. [5]
The compliance line: smoke seal and intumescent are two jobs
Rule — treat the smoke seal and the intumescent fire seal as two distinct requirements, and keep every rating with the tested assembly. Intumescent edge seals do not activate until roughly 180–200 °C, so in the early cold-smoke phase the perimeter is open unless a separate smoke seal (gasket or brush/fin) is present.
H-O converts the smoke-seal gasket material; the listed intumescent product is the door manufacturer's component, and its activation and rating belong to the tested assembly. Draw both requirements and cite the standards by designation; never let one part claim the other's rating. [9]
Specification Tools
Two tools to take you from "we're sealing a smoke door" to here's the gasket-and-barrier checklist for the drawing set: a requirement-driven gasket-set builder that assembles the layer list with its citations, and a side-by-side comparison of every fire/smoke family on this page.
1. Fire & smoke assembly gasket-set checklist builder
Check the requirements your assembly carries. The builder assembles the corresponding gasket, closure, and barrier layers into a checklist with the family, what to send with the drawing, and the citation language (material classes per TDS; assembly ratings by designation, listing with the tested assembly). The default selection below is pre-built for a typical smoke-and-draft-control door; every layer is also printed in the material reference section, so nothing here exists only behind a script.
Gasket-set checklist: 4 layers selected
Each checked requirement adds its layer below. The list is the starting bill of materials for the engineering review, not a certification: material classes (UL 94, ASTM E84) come from the grade TDS, and assembly ratings (UL 1784 / UL 555S / UL 1479) are cited by designation with the rating belonging to the tested assembly.
2. Side-by-side: fire & smoke family comparison matrix
Every family called out on this page, with construction, the class that drives its selection, the material-level methods its TDS cites, and the zone it serves. Click a column header to sort. Click any material name to jump to its accordion entry. Assembly ratings are not in this table because they belong to the tested assembly, not the material.
| Material | Construction | Selection class | Material methods on the TDS | Zone | |
|---|---|---|---|---|---|
| Perimeter and damper seals | |||||
| flame-resistant V-0 & BISCO® FR Silicone SpongeFlame-resistant silicone sponge | Closed-cell silicone sponge | Flame class (UL 94 V-0) | UL 94; ASTM E84; D1056 | Doors, dampers, firestop | |
| EPDM Closed-Cell FoamEPDM sponge | Closed-cell EPDM foam | Compression class | ASTM D1056; D395 | Fire & smoke doors | |
| Silicone Foam (BISCO® class)Cellular silicone | Cellular silicone foam | Elevated-temperature grade | ASTM D1056 (per TDS) | Fire & smoke dampers | |
| PORON® 4701 Series (4701 40V0)Microcellular urethane | Microcellular PU foam | Low compression set + V-0 | ASTM D3574; UL 94 (40V0 TDS) | Door / firestop closures | |
| Non-combustible barriers and layers | |||||
| Glass-Fibre Paper (MANNIGLAS® class)Inorganic barrier | Glass-fibre paper | Non-combustible / Class A | ASTM E84 (indices per TDS) | Barriers, firestop | |
| Muscovite & Phlogopite Mica SheetInorganic mica | Mica laminate sheet | High-temperature / non-combustible | Continuous ~500/700 C (per TDS) | Non-combustible barriers | |
| Low-Smoke / Low-Flame / Low-ToxicitySmoke-index layer | Low-smoke facing / barrier | Smoke / toxicity indices | ASTM E84 indices (per TDS) | Dampers, barriers | |
| Closed-Cell Neoprene FoamClosure foam | Closed-cell neoprene | Compression class (annular gap) | ASTM D1056 (per TDS) | Firestop closures | |
| PTFE-Coated FibreglassWoven-glass facing | PTFE-coated fibreglass | High-temperature facing | Per grade TDS | Non-combustible barriers | |
Skip ahead and request your engineering review now
If your drawing set already calls out a perimeter smoke seal, a damper seal, a barrier die-cut, or a firestop-adjacent closure, send it over for engineering review against the TDSs and the standards language.
Fire & smoke gasket failures you can prevent at spec
Fire and smoke assemblies fail quietly first: a seal that relaxed, a barrier that was combustible in a Class A location, a smoke seal assumed to be covered by an intumescent one, a closure treated as the firestop, or a submittal that stalls on a drawing note claiming a rating for a gasket. Five patterns cover most of what goes wrong, and each is a specification decision made before the first part is cut.
In life-safety assemblies, the paperwork is part of the part. A correct material with an undocumented class, or a drawing that claims an assembly rating for a component, costs more schedule at review than any cutting error. Cite material classes per TDS and assembly ratings by designation, and never write "fireproof" or "fire-rated gasket."
Show all 5 failure modes tap to expand
1. A perimeter seal specified by thickness, and the leakage class quietly expired
Fix — specify recovery and compression class, not gauge, and pick a low-compression-set material. A door or damper seal picked to fill the gap on day one is the right thickness once and the wrong spring forever; as it cycles and relaxes, contact force falls below the seal threshold and the assembly drifts out of its UL 1784 or UL 555S leakage class, months or years later.
State the closure force and the gap, choose the cellular class and compression behavior per ASTM D1056 / D395 on the TDS, and use PORON® microcellular urethane where low closure force and long-term seal-force retention matter most. [12]
2. A drawing note that claimed a rating for the gasket (or called it "fireproof")
Fix — cite the standard by designation, state the assembly requirement the gasket serves, and give the material only its material-level classes. A note reading "fire-rated gasket", "smoke-rated seal", or "fireproof" on a converted part stalls the submittal, because UL 1784, UL 10C, UL 555, UL 555S, and UL 1479 / ASTM E814 ratings belong to the tested assembly and its listing, not to a component.
Write the UL 94 or ASTM E84 class on the gasket callout, reference the assembly standard by designation, and let the tested door, damper, or firestop system carry the rating. [1]
3. The smoke seal left out because the intumescent seal was assumed to cover it
Fix — treat the smoke seal and the intumescent fire seal as two distinct line items. Intumescent edge seals do not activate until roughly 180–200 °C, so in the early, cold-smoke phase the door perimeter is open to smoke unless a separate smoke seal (a gasket, or a combined seal with a brush/fin) is present, which is exactly the window in which cold, toxic smoke migrates.
Draw both requirements: H-O converts the smoke-seal gasket material, the listed intumescent product is the door manufacturer's component, and each is cited against its own standard by designation. [9]
4. A combustible or high-smoke material where a Class A location needed non-combustible
Fix — match the layer to the location: an inorganic barrier where nothing may burn, a rated material class where a flame class is what the location needs. A gasket or barrier with no surface-burning evaluation can push a location out of its Class A requirement (ASTM E84 flame-spread 0–25, smoke-developed 450 or less), and a combustible foam has no place where an inorganic barrier belonged.
Use glass-fibre paper for a thin Class A barrier and mica sheet where sustained heat is present, and select any seal material by the ASTM E84 indices its TDS reports for the location. [7]
5. A firestop-adjacent closure treated as the firestop system
Fix — build to the listed UL 1479 / ASTM E814 system and let the converted closure be a documented component of it. A compressible closure or gasket ring around a penetration is not the firestop; substituting it for the listed sealant or wrap voids the F- and T-ratings, and a review will catch it. Size the closure to the annular gap from closed-cell or inorganic stock as part of the listed system, keep the rating with the tested system, and supply the closure's TDS and lot traceability as the component documentation. [5]
Material reference
Detailed specs for the fire and smoke families referenced on this page: the perimeter and damper seals (flame-resistant silicone sponge, EPDM foam, silicone foam, PORON® microcellular urethane), the non-combustible barriers (glass-fibre paper, muscovite and phlogopite mica sheet, PTFE-coated fibreglass), and the firestop and smoke-index layers (closed-cell neoprene closures, low-smoke/low-flame/low-toxicity).
Values are per the maker TDS on file for each grade with the method named; assembly standards are cited by designation only, with the rating belonging to the tested assembly. H-O die-cuts, kiss-cuts, slits, and kits every family to drawing.
Material class (per the maker TDS): UL 94 flammability, ASTM E84 surface-burning indices, ASTM D1056 / D395 cellular and compression-set data. Assembly rating (per the tested / listed assembly, by designation): UL 1784, UL 10C, UL 555, UL 555S, UL 1479 / ASTM E814.
Rule of thumb: write the material class on the gasket callout, and cite the assembly rating by designation with the listing belonging to the tested assembly.
Flame-Resistant Silicone Sponge (V-0 grades, BISCO® RS-Series)Door & damper smoke seals · UL 94 V-0 material class per TDS · ASTM E84 indices per grade
Cautious language is part of this material's spec: a V-0 material class does not make a gasket "fire-rated." H-O supplies the converted seal and its TDS; the tested door or damper carries the rating.
EPDM Closed-Cell FoamEconomical door perimeter seals · ASTM D1056 classes · ozone / UV durable
Where a flame class or wider temperature endurance drives the joint, the silicone sponge track takes over; EPDM is the durable, economical default for the ambient perimeter seal.
Silicone Foam (BISCO® class)Damper blade / frame seals · elevated-temperature endurance · per-grade TDS
Match the seal's temperature grade to the assembly's elevated-temperature rating, not to the ambient duty alone; the TDS range is what governs.
PORON® Industrial Microcellular Urethane (4701 Series, 4701 40V0)Precision low-set closures · ASTM D3574 methods · V-0 class on the 40V0 TDS
Specify the closure force and the gap, not just thickness; the compression-set resistance is what keeps the seal alive over the building's life.
Glass-Fibre Paper (MANNIGLAS® class)Non-combustible barrier layers · Class A surface burning per ASTM E84 · indices per TDS
Non-combustible is a different requirement from a flame class: glass-fibre paper does not burn at all, which is why it is the barrier layer where nothing may.
Muscovite & Phlogopite Mica SheetHigh-temperature non-combustible barrier · continuous to approx. 500 / 700 °C per TDS
Mica does not make an assembly "fire-rated"; it is a non-combustible barrier component with a documented continuous-service temperature on its TDS.
Low-Smoke / Low-Flame / Low-ToxicityThe smoke / toxicity index layer · ASTM E84 indices · per grade TDS
Specify the indices the location requires and read them off the grade TDS; the layer supports the smoke-control design, it does not certify it.
Closed-Cell Neoprene FoamFirestop-adjacent closures · ASTM D1056 classes · sized to the annular gap
The closure never substitutes for the listed sealant or wrap; it is a component of the listed UL 1479 / ASTM E814 system, with its own TDS and lot traceability.
PTFE-Coated FibreglassHigh-temperature woven-glass barrier / gasket facings · per grade TDS
Reach for this where a coated woven-glass facing suits the detail; per-grade properties govern, on the TDS.
SAE Pressed Felt (F-1–F-55) + Cork Pads (Plain MS113, Rubberized)Compliant liners, strike pads, leveling, anti-slip · ASTM D461 felt methods · F36 cork compressibility
None of these parts carries serious load; all are dimension-critical, which is exactly what die-cutting is for.
Fire & smoke materials: engineer-grade FAQ
Eleven of the questions we hear most from life-safety, architectural, and mechanical (HVAC) teams. If your question isn't here, send a drawing or call, engineering picks up.
Are these gaskets fire-rated or smoke-rated?
No gasket is, and no honest supplier will claim otherwise, or call one "fireproof". Fire, smoke, and leakage ratings are earned by the tested, listed assembly: the smoke-and-draft-control door tested to UL 1784, the fire door tested to UL 10C, the damper tested to UL 555 / UL 555S, the through-penetration firestop system tested to UL 1479 / ASTM E814.
What the materials on this page carry is their own documentation: material-level classes such as UL 94 V-0 and ASTM E84 surface-burning indices on the grade TDS, plus lot-code traceability. They are documented components of a rated assembly; H-O supplies the converted part and the paperwork, and the assembly's listing carries the rating. [1]
What is a smoke-and-draft-control door, and what does UL 1784 require?
It is a door assembly tested for air leakage to UL 1784, the basis of the "S" mark that NFPA 105 and the building code reference for smoke doors. The installed assembly must hold air leakage to 3.0 cfm/ft² of door opening at 0.10 in w.g., at ambient (75 °F) and at 400 °F. That number is difficult to reach without a listed perimeter gasket at the head, jambs, and meeting stiles, which is the smoke-seal gasket H-O to the door schedule.
The rating belongs to the tested door assembly; the gasket is its listed component. [1]
Smoke seal vs. intumescent seal: why does a door need both?
They do two different jobs at two different moments. The smoke seal (a gasket, or a combined seal with a brush/fin) closes the perimeter against cold and warm smoke from the very start of a fire. The intumescent seal stays dormant until roughly 180–200 °C, then expands to seal the gap against flame and hot gases. Because the intumescent does not activate early, there is a critical window in which toxic cold smoke migrates through an unsealed perimeter unless a separate smoke seal is present.
H-O converts the smoke-seal gasket material; the listed intumescent product is the door manufacturer's component, and its rating belongs to the tested door. [9]
What seals a smoke damper, and what is a UL 555S leakage class?
The blade-edge, jamb, and frame seals make a smoke damper meet its UL 555S leakage class: Class I is 8 cfm/ft² at 4 in w.g. (Classes II and III are higher), and codes generally require Class I or II with an elevated-temperature rating not less than 250 °F. A combination fire/smoke damper is listed to both UL 555 and UL 555S.
H-O converts those seals from silicone foam and flame-retardant silicone sponge grades whose TDSs carry the temperature range the damper maker calls out; the leakage class and the temperature rating belong to the tested damper. [4]
Mica vs. glass-fibre: which non-combustible barrier goes where?
Both are inorganic and non-combustible; the split is temperature. Glass-fibre paper (the MANNIGLAS®-class grades) is the thin barrier layer where you need a Class A surface-burning result (ASTM E84 flame-spread 0–25, smoke-developed 450 or less, indices on the grade TDS).
Mica sheet steps in where the interface also sees sustained heat: muscovite holds to about 500 °C continuous and phlogopite to about 700 °C, both dimensionally stable at flame temperature, with glass-fibre-reinforced flexible grades for die-cutting. Choose glass-fibre for a thin Class A layer, mica for higher sustained temperature. [7]
What does ASTM E84 Class A mean for a material?
ASTM E84 (the Steiner Tunnel test) reports two material-level index values: a flame-spread index (FSI) for how fast flame travels across the surface, and a smoke-developed index (SDI) for how much smoke the sample gives off. Class A is the top band: FSI of 0 to 25, with a smoke-developed index of 450 or less (the SDI limit is 450 for all classes).
It is a surface-burning class carried on the maker TDS for the grade, and it is a material property, not an assembly rating. Use it to select barrier and facing materials for a Class A location. [7]
How do firestop-adjacent gaskets relate to a UL 1479 / ASTM E814 system?
A through-penetration firestop is a tested system, and its performance is an F-rating (no flame passage) and a T-rating (no temperature rise above 325 °F on the unexposed side), harmonized between UL 1479 and ASTM E814. A compressible closure or gasket ring around the penetrant is a component of that listed system, not the firestop itself; substituting it for the listed sealant or wrap voids the ratings.
H-O sizes the closure to the annular gap as a documented component of the listed system, and the F- and T-ratings stay with the tested system. [5]
Does H-O make intumescent seals or firestop systems?
No. H-O and converts the gasket, closure, and barrier materials that go into these assemblies; it does not manufacture listed intumescent seals or listed firestop systems, and it does not build the door or damper hardware. The listed intumescent seal is the door manufacturer's or seal-maker's product, and the firestop system is the system supplier's listed assembly. H-O's part is the converted smoke-seal gasket, barrier die-cut, or firestop-adjacent closure, supplied as a documented component with its maker TDS and lot traceability. [6]
Silicone or EPDM for a door perimeter smoke seal?
EPDM closed-cell foam is the economical, ozone- and UV-durable default where the perimeter seal needs no flame class of its own, with compression classes per ASTM D1056. Move to flame-resistant silicone sponge (V-0 grades, BISCO® RS-series) when a UL 94 flame class or wider temperature endurance drives the joint, with the V-0 class carried on the grade TDS. Match the compression class to the real closure force either way; the assembly's UL 1784 rating is earned by the tested door regardless of which material track you choose. [12]
Can H-O kit a whole door or damper seal set?
Yes: perimeter gaskets, meeting-stile seals, damper blade and frame seals, barrier die-cuts, and firestop-adjacent closures can ship as kitted sets, one kit per opening or damper, parts on liner in assembly order, with lot-code TDS records per material. That is exactly the documentation a submittal and an inspection want to see, since it shows each converted component and its material class alongside the assembly's own listing. [8]
Does H-O mold or extrude these materials, or convert them?
H-O and converts sheet, roll, and blanket stock to drawing; molding and extrusion are not in-house services, and extruded seal profiles are coordinated through a partner network (made-to-order, 4–6 week tooling). Conversion runs in Winsted, Connecticut under an ISO 9001:2015 certified quality management system with material traceability and lot-code TDS records. What ships is custom, made to order to your door schedule, damper drawing, or penetration detail. [13]
Glossary: terms used on this page
Quick reference for the fire, smoke, and barrier terminology used throughout. Each entry links to the relevant standard or test method where applicable. Every rating term is defined as belonging to the tested assembly, not the material.
UL 1784 (by designation)
The standard for air-leakage tests of door assemblies and other opening protectives: 3.0 cfm/ft² of opening at 0.10 in w.g., at ambient and 400 °F, per [1]. It evaluates the tested door assembly (the basis of the smoke-and-draft-control "S" mark), not its component gaskets, and is cited here by designation.
UL 10C / UBC 7-2 (by designation)
UL 10C is the positive-pressure fire test of door assemblies (NFPA 252 is the companion), which better simulates real-fire pressure than the older neutral-pressure method; UBC 7-2 [2] is the legacy Uniform Building Code fire-door test, cited by designation. The fire rating belongs to the tested door assembly.
UL 555 & UL 555S (by designation)
UL 555 is the fire-damper standard; UL 555S [4] is the smoke-damper standard, with leakage Class I / II / III (Class I = 8 cfm/ft² at 4 in w.g.) and an elevated-temperature rating not less than 250 °F. Both attach to the tested damper; a combination fire/smoke damper is listed to both.
UL 1479 / ASTM E814 (by designation)
F-rating & T-rating
The two firestop performance ratings from UL 1479 / ASTM E814 [5]. The F-rating is the whole-hour time the system holds against flame passage; the T-rating is the time before any thermocouple on the unexposed side rises more than 325 °F above ambient. Both belong to the tested system, never to a single converted material.
ASTM E84 (Steiner Tunnel) / Class A
The surface-burning test for building materials, per [7], reporting a flame-spread index (FSI) and a smoke-developed index (SDI). Class A = FSI 0–25 and SDI 450 or less. This is a material-level class on the maker TDS, used to select barrier and facing materials.
Intumescent seal (context)
A material that expands when heated (typically activating around 180–200 °C, expanding many times its volume to char) to seal a door or damper gap against flame. It is the listed door/damper manufacturer's component, and its rating belongs to the tested assembly; H-O converts the separate smoke-seal gasket, not the listed intumescent product. See NFPA 105 [9].
Smoke seal / smoke-and-draft-control
The perimeter gasket (or a combined seal with a brush/fin) that limits air and smoke leakage around a door leaf from the start of a fire, before any intumescent activates. On a smoke-and-draft-control door it is a listed component of an assembly tested to UL 1784 [1].
Non-combustible barrier
An inorganic layer that does not burn, melt, or add fuel: glass-fibre paper or mica sheet into barrier pieces. Non-combustibility is a different requirement from a flame class (a V-0 foam self-extinguishes; an inorganic barrier does not ignite at all). Surface-burning behavior is reported per ASTM E84 [7] on the grade TDS.
Compression set
The permanent deformation a seal keeps after sustained compression, measured per ASTM D395 [13]. It is the property that decides whether a perimeter or damper seal still holds its leakage class years later; a low-compression-set material keeps its seal force alive over the building's life.
Muscovite / phlogopite mica
The two mica chemistries used as non-combustible barrier sheet: muscovite holds to about 500 °C continuous, phlogopite to about 700 °C, both dimensionally stable at flame temperature, with glass-fibre-reinforced flexible grades for die-cutting. Continuous-service temperatures are per the grade TDS.
Rating belongs to the tested assembly
The honesty rule for fire and smoke claims: UL 1784, UL 10C, UL 555, UL 555S, and UL 1479 / ASTM E814 ratings attach to the tested door, damper, or firestop system and its listing, not to its component materials. A converted gasket carries its own material classes and supports a rated assembly without inheriting its rating; never "fireproof" or "fire-rated gasket."
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
Standards, test methods & technical references
The standards, test methods, and maker technical data sheets cited throughout this page. Assembly standards are cited by designation: they evaluate tested door, damper, and firestop assemblies, and the rating belongs to the tested / listed assembly. Standards editions current as of July 2026; verify against the publishing body before final spec. H-O converts materials tested to the material-level methods on the source maker's TDS; H-O does not certify assemblies or independently certify materials unless explicitly stated on the quote.
[1] UL 1784 (by designation)
Standard for Air Leakage Tests of Door Assemblies and Other Opening Protectives. 3.0 cfm/ft² of opening at 0.10 in w.g., ambient and 400 °F; basis of the smoke-and-draft-control door "S" mark. Evaluated on the tested door assembly; cited by designation. ul.com (UL 1784)
[2] UL 10C / UBC 7-2 (by designation)
Standard for Positive Pressure Fire Tests of Door Assemblies (positive-pressure method; NFPA 252 companion). UBC 7-2 is the legacy Uniform Building Code fire-door test, cited by designation. The fire rating belongs to the tested door. ul.com (UL 10C)
[3] UL 555 (by designation)
Standard for Fire Dampers. The fire-damper standard; a combination fire/smoke damper is listed to both UL 555 and UL 555S. Cited by designation; the rating belongs to the tested damper. ul.com (UL 555)
[4] UL 555S (by designation)
Standard for Smoke Dampers. Leakage Class I / II / III (Class I = 8 cfm/ft² at 4 in w.g.); elevated-temperature rating not less than 250 °F. Evaluated on the tested damper; cited by designation. ul.com (UL 555S)
[5] ASTM E814 (by designation)
Standard Test Method for Fire Tests of Penetration Firestop Systems. Yields the F-rating (flame passage) and T-rating (325 °F rise on the unexposed side); harmonized with UL 1479. Ratings belong to the tested system. astm.org (E814)
[6] UL 1479 (by designation)
Standard for Fire Tests of Through-Penetration Firestops. Harmonized with ASTM E814; the IBC references both as acceptable methods. The F- and T-ratings belong to the tested firestop system; a gasket or closure is a component. ul.com (UL 1479)
[7] ASTM E84 (material-level)
Standard Test Method for Surface Burning Characteristics of Building Materials (Steiner Tunnel). Flame-spread index (FSI) and smoke-developed index (SDI); Class A = FSI 0–25, SDI 450 or less. A material-level method reported on maker TDSs. astm.org (E84)
[8] NFPA 80 (by designation)
Standard for Fire Doors and Other Opening Protectives: the installation and maintenance requirements for listed fire-door assemblies. Cited by designation as the code context the tested door assemblies live in. nfpa.org (NFPA 80)
[9] NFPA 105 (by designation)
Standard for Smoke Door Assemblies and Other Opening Protectives: references UL 1784 for air leakage and defines smoke-and-draft-control door requirements. Cited by designation as design context. nfpa.org (NFPA 105)
[10] NFPA 92 (by designation)
Standard for Smoke Control Systems: the design standard for engineered smoke-control, including the dampers and plenums the smoke-index materials support. Cited by designation. nfpa.org (NFPA 92)
[11] UL 94 (material-level)
Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances (HB, V-0, V-1, V-2 classes). A material-level flammability class carried on the maker TDS (e.g. V-0 on the rated silicone-sponge and PORON® grades). ul.com (UL 94)
[12] ASTM D1056 (material-level)
Standard Specification for Flexible Cellular Materials, Sponge or Expanded Rubber. Type/Class/Grade classification for the EPDM, neoprene, and silicone-foam seal materials; reported on the grade TDS. astm.org (D1056)
[13] ASTM D395 (material-level)
Standard Test Methods for Rubber Property, Compression Set. The recovery-after-compression method behind seal-force retention; reported on the grade TDS (Method B most common). astm.org (D395)
Updated . Standards editions and links current at publication; verify against the publishing body before final spec. Ratings cited by designation attach to the tested / listed assembly; H-O converts materials aligned to the material-level methods via the maker TDS and does not certify assemblies or independently certify materials unless explicitly stated on the quote. Lot-specific documentation available on request. No maker named in this block is a competitor of H-O.
To review your fire or smoke gasket, closure, or barrier, send:
- The assembly (fire/smoke door, damper, penetration, barrier)
- The requirement it must meet (UL 1784 leakage, UL 555S class, firestop system no., ASTM E84 class)
- Door schedule, damper drawing, or penetration detail
- The gap or clearance to close
- Closure force and any seal-force target
- Elevated-temperature and non-combustibility needs
- Any smoke / toxicity index requirement
- Adhesive / liner / pull-tab requirements
- Prototype and annual volume
Get a fire & smoke materials engineering quote
Send a door schedule, damper drawing, or penetration detail. We typically respond within one business day with a material recommendation, prototype lead time, and TDS verification against your leakage limit, flame and smoke class, elevated-temperature demand, and the standards language, framed correctly so the rating stays with the tested assembly.
See also: related H-O application pages
Engineering content for the adjacent general-construction sub-applications and the parent hub. Each page covers material selection, failure modes, and converter-side process detail for its application family.
Sibling sub-application
Expansion joint systems
Die-cut movement-joint seals specified by movement capacity: precompressed foam sealant tape, closed-cell backer, and EPDM / neoprene / silicone compression seals.
Read the page
Sibling sub-application
Duct & pipe thermal insulation
Die-cut thermal insulation, lagging, and jacketing for HVAC duct and pipe, where thermal, condensation, and surface-burning requirements meet.
Read the page
Sibling sub-application
Building electrical & arc flash
Die-cut dielectric barriers, arc-flash and insulation materials for building electrical rooms, switchgear, and panels, cited by designation.
Read the page
Industry hub
General construction
The full general-construction application family: envelope sealing, movement joints, roofing and glazing, acoustic isolation, equipment isolation, fire and smoke, and building electrical.
Read the page
Material data & standards. All compression, temperature, surface-burning, and flammability values on this page are taken from the source maker's technical data sheets with the method named (ASTM E84, D1056, D395, D3574; UL 94 classes per the listed grade TDSs).
Assembly standards (UL 1784, UL 10C, UL 555, UL 555S, UL 1479 / ASTM E814, NFPA 80 / 105 / 92) are cited by designation only: they evaluate tested door, damper, and firestop assemblies, the fire, smoke, and leakage rating belongs to the tested / listed assembly, and the materials on this page support designs evaluated to them.
H-O converts materials; H-O does not manufacture doors, dampers, listed intumescent seals, or listed firestop systems, does not test or list assemblies, and does not independently certify materials against the standards unless explicitly stated on the quote. Verify against the maker TDS and the assembly's own listing.
Conversion scope. H-O and converts sheet, roll, and blanket stock to drawing in Winsted, Connecticut: die-cut and kiss-cut gaskets, closures, and barriers, slit tape, waterjet-cut thick sections, laminations, and kitted seal sets, with material traceability and lot-code TDS records. H-O is a die-cutter and converter, not a molder or an extruder; molded and extruded profiles are coordinated through a partner network (made-to-order, 4–6 week tooling). Lead-time and MOQ details are in the process strip and the quote form above.